Packed column distillation system

Abstract

An improved packed column distillation system, which may be particularly advantageous for use with cryogenic distillation such as the cryogenic distillation of air, wherein external heat is provided at the column wall, especially at a stripping section of the column, to vaporize liquid formed on the inner surface of the column wall resulting in improved separation efficiency with lower packed bed height.

We claim: 
     
       1. A method for carrying out distillation comprising providing a distillation column having a column wall with an inner surface and an outer surface, passing vapor and liquid countercurrently in the column over mass transfer elements comprising packing and forming liquid on the inner surface of the column wall, characterized by providing external heat at the column wall by condensing fluid on the column wall in an amount sufficient to vaporize at least some of the liquid formed on the inner surface of the column wall. 
     
     
       2. The method of claim 1 wherein at least some of said condensed fluid is passed into the column. 
     
     
       3. The method of claim 1 wherein the distillation method is the cryogenic distillation of air carried out with a double column system having a lower pressure column and a higher pressure column having a feed air stream and the column is the lower pressure column of the double column system. 
     
     
       4. The method of claim 3 wherein the fluid is taken from the feed air stream to the higher pressure column. 
     
     
       5. The method of claim 3 wherein the fluid is taken from at least one of the higher pressure column and the lower pressure column. 
     
     
       6. The method of claim 3 further comprising the use of an argon column wherein the fluid is taken from the argon column. 
     
     
       7. The method of claim 6 wherein condensed fluid is returned to the argon column. 
     
     
       8. The method of claim 1 wherein the external heat is provided at the outer surface of the column wall. 
     
     
       9. The method of claim 1 wherein the external heat is provided at the inner surface of the column wall. 
     
     
       10. The method of claim 1 wherein the vapor and liquid passed countercurrently in the column comprises at least two of oxygen, nitrogen and argon.